Game Center comes with iOS 4. You do not need to download the app. You are also unable to delete it so enjoy it.
Yes. If you update your iPhone's software using iTunes it will lock your iPhone again. You will then need to unlock it again.
Yes. Sign in to Game Center on the "original phone". At some points within the game, it will be saved. In your "new" phone, install Tiny Tower, run it, and when prompted, login to Game Center. It should ask if you want to Restore from the saved game.
Siri
Yes. Just sync your iPhone with your computer and download the 2.2 software. The new software should wipe out the jailbreak, so just re-install it.
no but it can do all the multitasking and stuff
The new iPod 2G comes with 2.1.1 firmware
Yes
with the new 3.0 software update it is expected to be possible
software updates for the iphones, ipads, and ipods all use itunes. the 3gs is capable of running apple's newest 5.0.1 software which brings icloud, notification center, and imessage to your device as well as many new features and much better battery life
its a software. i believe its coming out Friday April 9th. my friend told me the update has something to do with multitasking apps..
you should i have a iphone 3g and since the 4.0 update it looks better and it has so many new features you should its awesome
They have games for iPhone and BlackBerry for Twilight New Moon and not for PS2